C#•2y ago

❔ Nullability issue

I have this code

        public bool Equals(Money money)
        {
            if (money is null)
            {
                return false;
            }

            if (ReferenceEquals(this, money))
            {
                return true;
            }

            return Currency.CurrencyCode == money.Currency.CurrencyCode && Amount == money.Amount;
        }

        public bool Equals(Money money)
        {
            if (money is null)
            {
                return false;
            }

            if (ReferenceEquals(this, money))
            {
                return true;
            }

            return Currency.CurrencyCode == money.Currency.CurrencyCode && Amount == money.Amount;
        }

and i get this warning. How can i fix it?

10 Replies

Angius•2y ago

IEquatable has method .Equals() that takes a nullable parameter So just change Equals(Money money) to Equals(Money? money)

_giuraemanuelOP•2y ago

Hey. Thanks for your answer! But Money can't be null whatsoever so how does that help? Sorry if my question is dumb.

Angius•2y ago

IEquatable requires the method Equals() to also handle a null That's all there is to it

_giuraemanuelOP•2y ago

Hmm. Okay. Thank you!

Angius•2y ago

A class implementing an interface must implement it entirely and verbatim

_giuraemanuelOP•2y ago

Fair enough. I wasn't exactly familiar with equality implementation and stuff so that's why i asked. Thanks once again!

Angius•2y ago

Anytime 👌

Sagar viradiya•2y ago

@GEmanuel Can you share updated code.

_giuraemanuelOP•2y ago

        public bool Equals(Money? money)
        {
            if (money is null)
            {
                return false;
            }

            if (ReferenceEquals(this, money))
            {
                return true;
            }

            return Currency.CurrencyCode == money.Currency.CurrencyCode && Amount == money.Amount;
        }

        public override bool Equals(object? obj)
        {
            return obj is Money money && Equals(money);
        }

        public override int GetHashCode()
        {
            int hash = 17;
            hash = hash * 23 + Currency.GetHashCode();
            hash = hash * 23 + Amount.GetHashCode();
            return hash;
        }
    }

        public bool Equals(Money? money)
        {
            if (money is null)
            {
                return false;
            }

            if (ReferenceEquals(this, money))
            {
                return true;
            }

            return Currency.CurrencyCode == money.Currency.CurrencyCode && Amount == money.Amount;
        }

        public override bool Equals(object? obj)
        {
            return obj is Money money && Equals(money);
        }

        public override int GetHashCode()
        {
            int hash = 17;
            hash = hash * 23 + Currency.GetHashCode();
            hash = hash * 23 + Amount.GetHashCode();
            return hash;
        }
    }

Sorry for the late reply. Here you go. Based on this: https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/statements-expressions-operators/how-to-define-value-equality-for-a-type

How to define value equality for a class or struct - C# Programming...

Learn how to define value equality for a class or struct. See code examples and view available resources.

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity. Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Nullability issue